1. Field of the Invention
This invention relates to an ink reservoir for an ink jet printer, and, more particularly, it is concerned with an ink reservoir for an ink jet printer, which has solved problems in connection with an ink storing tank and disposal of a waste ink collecting tank.
2. Description of the Prior Art
A polychromatic ink jet printer is provided with a plurality of ink cassettes, each containing therein an ink tank which stores different color of ink. These ink cassettes are installed in the printer in a freely mountable and dismountable manner. The inks in various colors stored in the ink cassettes are used for printing numerical figures and letters, or for producing picture images in monochrome or in polychrome using the various ink colors in combination. The colors of the ink which are typically used are cyan, magenta, yellow and black. For letter printing, black ink is usually used. For picture images output, black and the three other colors in combination are used.
In office work in general, letter printing is the main function of the printers, for preparing documents and reports on various activities. Even in those printers having multi-color printing functions and being capable of recording picture images such as graphical representations, etc., the prevailing work in their actual use is still the printing of letters and characters. As a consequence of this, the black ink is consumed much more rapidly than the inks in other colors. Needless to say, since the black ink is used not only for letter printing, but also for picture images as a matter of course, consumption of the black ink (or any color of ink used in large quantity for letter printing) is remarkably high in comparison with that of the ink of other colors. On special occasions other than the office work in general, ink of the other colors, e.g., blue may be used much more than ink for the letter printing. In such case, the ink cassette of the ink with the highest consumption requires frequent replacement as a matter of course.
On the other hand, when poor letter printing takes place in an ink jet printer, it is necessary from time to time to remove undesirable conditions such as foaming, etc. which are liable to cause poor printing. More concretely, in order to restore the normal printing function, a cap is put on the nozzle to draw out ink from it by a pumping pressure so that the ink may again be regularly fed to the nozzle end. Also, in order to avoid poor printing, there have been adopted various methods for example ink is ejected toward a cap without regard to printing to thereby maintain the distal end of the nozzle in a condition which enables normal printing to be always carried out.
Particularly, in an ink jet printer of the "on-demand" type, ink if often ejected without regard to printing (i.e. waste ink). Such waste ink should naturally be recovered, and the thus recovered waste ink should be stored. For this purpose, a waste ink tank or the like can be used. Such waste ink tank may be useful so far as its volumetric capacity is sufficiently large, but, to be consistent with a general tendency to size-reduction in ink jet printers as a whole, a waste ink tank per se cannot be made large. As a consequence of this, ink absorbing material in the waste ink tank where such waste ink is stored must be replaced at a definite time interval to avoid occurrence of problems such as overflowing of waste ink.
Moreover, when a waste ink tank is installed in the printing apparatus in an exchangeable manner, apart from the ink cassettes to store therein inks in a plurality of different colors, the space for receiving such ink cassettes and the waste ink tank becomes inevitably large with the consequent hindrance of size-reduction of the printing apparatus.